1. Technical Field
The present disclosure relates to a perpendicular magnetic recording head that records information by applying a perpendicular magnetic field to a recording medium.
2. Description of the Related Art
As is widely known, a perpendicular magnetic recording head has a main magnetic pole layer, a return path layer (auxiliary magnetic pole layer), and a coil layer that provides a recording magnetic field to the main magnetic pole layer and the return path layer. The main magnetic pole layer and the return path layer are laminated with a nonmagnetic layer therebetween and form a surface that opposes a recording medium (hereinafter this surface is referred to as “recording medium-opposing surface”). The area of the main magnetic pole layer exposed in the recording medium-opposing surface is sufficiently smaller than the area of the return path exposed in the recording medium-opposing surface, and the main magnetic pole layer is magnetically coupled to the return path layer at the side remote from the recording medium-opposing surface in the height direction. The main magnetic pole layer includes a pole straight part exposed in the recording medium-opposing surface and a flared part that connects to the back end of the pole straight part in the height direction. Once electricity is supplied to the coil layer, a recording magnetic field is induced between the main magnetic pole layer and the return path layer and enters a hard film of the recording medium in a perpendicular fashion from the front end surface of the main magnetic pole layer exposed in the recording medium-opposing surface. The recording magnetic field passes through a soft film of the recording medium to thereby complete magnetic recording on the recording medium in the portion that opposes the main magnetic pole layer.
According to a proposal regarding a perpendicular magnetic recording head, the pole straight part (the portion that is exposed in the recording medium-opposing surface) of the main magnetic pole layer formed on the nonmagnetic layer is rendered a trapezoidal shape (bevel shape) narrowed at the nonmagnetic insulating layer-side when viewed from the recording medium-opposing surface-side. This is to increase the recording density and to prevent generation of fringing at the time of skew. A perpendicular magnetic recording head having such a trapezoidal pole straight part is disclosed in Japanese Unexamined Patent Application Publication No. 2002-197611, US2003021063 A1 and US 2003112555 A1.
However, even when the cross-sectional shape of the pole straight part of the main magnetic pole layer is rendered a trapezoidal shape, the magnetic flux heading toward the recording medium from the pole straight part broadens in the track-width direction under a high recording magnetic field, and the side fringe width is increased thereby. The increase in side fringe width may lead to deletion of information magnetically recorded on a track adjacent to the track on which the recording is currently carried out, which is a problem. In the related art, the intensity of the recording magnetic field is controlled not to exceed a certain level to keep, the side fringe width small, but this is disadvantageous for increasing the recording density.